The present invention is generally directed to systems and methods for tracking the position of objects.
Position-tracking systems seek to identify the location of mobile objects in real-time and are used in a wide variety of applications, including transportation, logistics management, healthcare, security, etc. Position-tracking systems that can provide continuous location information are desirable for applications that require non-interrupted visibility of the mobile object through a journey. For objects that are moved with a vehicle (such as inter-modal shipping containers or trailers), being able to locate the position of the objects in real-time can help improve the efficiency of supply-chain and inventory management while reducing the loss in productivity of assets. As businesses increasingly depend on a global supply chain and distribution networks, more goods and assets are being moved around for longer distances and with more parties involved in the process. In order to facilitate an automated, error-free data exchange for logistics management, the availability of continuous information about these assets in real-time is more valuable than “discrete” information that is only available for certain regions, albeit with perhaps higher position resolution.
Existing position-tracking systems typically employ satellite, radio wave or other wireless technologies. However, such systems typically suffer from limitations caused by line-of-sight requirements for location signals and/or interference caused by the environment in which they operate (e.g., multi-path fading or radio waves in an indoor setting). In addition, although much effort has gone into extending the operating range for Global Positioning System (GPS) and GPS-like technologies with more and more sophisticated software implementations, GPS systems are still generally ineffective and unreliable for location tracking indoors or in other environments where obstructions to the satellite signals present challenges. Further, other non-GPS based position technologies that have been proposed to date are largely based on a “local GPS” system using an assembly of locally deployed wireless antennas to mimic the function of the GPS satellites. Due to the high cost of designing and implementing such systems, however, they remain a costly proposition.
Other object-tracking technologies, such as RF ID tags or bar codes, may be acceptable for tracking objects where the objects generally travel only within a small, controlled environment, such as a warehouse, where their travel paths are static and well-defined. These technologies, however, cannot suitably track the position of the object once it leaves the controlled environment.